The invention relates to an apparatus for the sterilization during the filling of preferably liquid foodstuffs into packaging containers, having a preheating zone, a sterilizing zone, a drying zone, a filling zone and a closure zone.
For technical reasons of hygiene and keeping properties, special attention must always be given to sterilization when more particularly liquid foodstuffs are filled into packaging containers. The actual sterilization is performed by known processes, in which the surfaces of the packagings which are to be sterilized must come into contact for a predetermined period of time with a sterilizing agent which must then--i.e., prior to the actual filling operation--be again removed from the surface of the packaging (DE 30 36 972 C2).
To make the sterilizing operation as economical as possible, the changeover has been made to the use of H.sub.2 O.sub.2 --i.e., hydrogen peroxide--as the sterilizing agent. An optimum effect is achieved if the packagings to be filled are heated in a first zone (preheating zone), to enable the subsequent treatment to be performed as quickly and efficiently as possible. The packages continuously move forwards and are conveyed from the preheating zone into the following sterilizing zone, in which they are wetted with the sterilizing agent, preferably H.sub.2 O.sub.2. To this end the liquid H.sub.2 O.sub.2 is atomized by means of hot compressed air or superheated steam to give an H.sub.2 O.sub.2 aerosol, so that no larger and heavier droplets can be deposited on the surface of the packaging which might no longer be removable during the following rinsing operation. It has been found that the brief wetting with the H.sub.2 O.sub.2 aerosol in a hot atmosphere is adequate for the reliable extermination of any bacteria present. For the removal of the H.sub.2 O.sub.2 aerosol from the packagings, the packagings then pass through a further zone, the so-called drying zone, in which the packagings are flushed at atmospheric pressure with flowing superheated steam. The packagings are then filled, also using known means, in a filling zone.
Since sterile conditions must be present in all the aforementioned five zones, the individual zones are substantially partitioned-off from the exterior, to enable the packagings to be conveyed inside a germicidal atmosphere. Although the use of H.sub.2 O.sub.2 has proved satisfactory for sterilization, with the filling machines used care must be taken that none of the H.sub.2 O.sub.2 atmosphere gets into the room in which the filling machine is situated, for economic and also health reasons (hydrogen peroxide is a strong oxidant).
Moreover, particularly before the start of the shift, each individual zone must first be flushed with a quantity of H.sub.2 O.sub.2 aerosol such as will reliably sterilize or remove any contaminated air which may be present. For this purpose hitherto in order to achieve the required sterilization, it was necessary to flush out the H.sub.2 O.sub.2 vapour in the individual chambers of the different zones for a particular period of time. This called for an expensive construction and a correspondingly heavy consumption of H.sub.2 O.sub.2, since the individual chambers in the conveying direction of the packagings can never be really adequately sealed.
It is therefore an object of the invention so to design and further develop the aforementioned sterilization apparatus described in detail hereinbefore that the period during which the individual zones are acted upon with the sterilizing agent can be shortened and that the quantity of the sterilizing agent to be used can be minimized. In addition, a simple construction is desirable, so that the expenditure always required for cleaning and maintenance is also minimized.